HYDROGEN IN METALS / METALHYDRIDES Andreas Zttel CONTENTS 1) - - PowerPoint PPT Presentation

CONTENTS 1) Hydrogen interaction with surfaces 2) Hydrides 3) Stability and hydrogen density 4) Complex hydrides HYDROGEN IN METALS / METALHYDRIDES

Andreas Züttel

HYDROGEN DENSITY

50 100 150 200 10 20 30 Hydrogen density [kg/m3] Hydrogen density [kg H2/ 100kg storage material]

Andreas Züttel, Switzerland, 17.07.14

• liq. hydro-

carbons comp. H2 gas

• liq. H2
• liq. natural

gas

NH3

carbon hydrates

INTERACTION OF GASES WITH SURFACES

S T H G Δ ⋅ − Δ = Δ

Ref: W. Göpel, B. Kühnemann, Z. Phys. Chem. N.F. 122 (1980), p. 75

CHEMISORPTION OF GASES ON METAL SURFACES

Ref: M. Henzler, W. Göpel, „Oberflächenphysik des Festkörpers, Teubner Studienbücher Physik, B. G. Teubner Stuttgart 1991, p. 474

ΔEchem≈ 0.25 eV

LENNARD-JONES POTENTIAL

Ref.: J. E. Lennard-Jones, Trans. Faraday Soc. 28 (1932), pp. 333.

• L. Schlapbach, Chapter 1, L. Schlapbach (Ed.) in Intermetallic Compounds I, Springer Series Topics in Applied

Physics, Vol. 63, Springer–Verlag, 1988, p. 10.

Andreas Züttel, Switzerland, 17.07.14 6

BINARY HYDRIDES

Ref.: Gottfried Brendel, Kapitel: Hydride, Ullmanns Encyklopädie der technischen Chemie, 4. neubearbeitete und erweiterte Auflage, Band 13 (1977), pp. 109-133, Verlag Chemie Weinheim New York

DISCOVERY OF HYDROGEN ABSORPTION IN METALS

Thomas GRAHAM, born Dec. 20, 1805, Glasgow, Scot., died

• Sept. 11, 1869, London, Eng.

British chemist often referred to as the father of colloid chemistry. Educated in Scotland, Graham persisted in becoming a chemist, though his fat- her disap- proved and with- drew his support. He then made his living by writing and teaching. He was a professor at a school in Edinburgh (1830–37) and at University College, London (1837– 55), and was master of the mint (1855–69). In his final paper he described palladium hydride, the first known instance of a solid compound formed from a metal and a gas.

Ref.: Thomas Graham„On the Occlusion of Hydrogen Gas by Metals“, Proc. Royal Soc. 16 (1868), pp. 422

8

HYDROGEN ABSORPTION IN METALS

• Ph. Mauron, M. Bielmann, EMPA, Switzerland

9

HYDROGEN ABSORPTION IN METALS

0 sec (vacuum) 5 sec (8 bar H2) 8 sec (8 bar H2) 15 sec (8 bar H2) 20 sec (8 bar H2) 30 sec (7 bar H2) 45 sec (6 bar H2) 60 sec (5 bar H2) ZrMn1.5

HYDROGEN IN AND ON PALLADIUM

THERMO DESORPTION SPECTROSCOPY After exposing Pd(111) at 115 K to equal doses of H2 and D2 a much stronger desorption of α-H than α-D is observed apparently due to faster H than D absorption into α-states. Only minor HD desorption was ob-

• served. Apparently the gas which was

dosed second bypassed the chemi- sorption state. α: chemisorbed hydrogen at the surface β: interstitial hydrogen

Ref.: G. E. Godowski, R. H. Stulen, T. E. Felter, J.

• Vac. Sci. Technology A5 (1987), pp. 1103

α β

HYDROGEN IN AND ON PALLADIUM

Andreas Züttel, IfRES (2005) 12

THERMODYNAMICS OF HYDRIDES

ΔH0 = 2/n·ΔHf M + n/2 H2 MHn

H2

ΔHf M + n/2 H2 → MHn

( ) ( ) ( )!

" # $ % & Δ − Δ − Δ ⋅ = Δ

2

2 2 H H n M H MH H n H

n

( ) ( ) ( )!

" # $ % & − − ⋅ = Δ

2

2 2 H S n M S MH S n S

n

S0(MHn) ≈ S0(M) → ΔS0 ≈ -S0(H2) S0(H2) = 130 JK-1mol-1 ΔH

= 0 = 0 ≈ 0

HYDROGEN IN METALS

Ref.: P. Nordlander, J. K. Norskov, and F. Besenbacher, J. Phys. F. Metal Phys. 16:9 (1986), pp. 1161-1171, J.K. Norskov and F. Besenbacher, J. of the Less-Common Metals 130 (1987), pp. 475-490

METAL H n r

EFFECTIVE MEDIUM THEORY

Jens Norskov

Andreas Züttel, Switzerland, 17.07.14 1 4

HEAT OF SOLUTION

LATTICE GAS

The free energy F = U - T·S is

ln exp

H

• HH

N N F kT kT ε ε + " # = − − % & ' (

∑

N : total number of sites NH : number of H ε0 : H binding energy NHH : number of nearest neighbour H-pairs ε : H-H pair interaction energy

• Ref. Ronald Griessen, VU Amsterdam, NL

Hemmes H, Salomons E, Griessen R, Sänger P, Driessen A., Phys Rev B Condens Matter. (1989);39(15):10606-10613.

ε ε

HH

• H

N N E + =

ε ε0

ISOTHERM

• Ref. Ronald Griessen, VU Amsterdam, NL

ln ) ( ln 2 1 → → ⋅ ⋅ ≅ ⋅ ⋅ ⋅

H H

c p c T k T p p T k

) ( 1 ln

2 1 =

− ⋅ ⋅ + − ⋅ ⋅

i i i

c n c c T k ε

b dis

n T p p T k ε ε ε − ⋅ + ⋅ = ⋅ ⋅ 2 ) ( ln

H H b H

c c k T c n T p p T k − ⋅ ⋅ + − ⋅ ⋅ + = ⋅ ⋅ ⋅ 1 ln ) ( ln

2 1 2 1

ε ε ε

ΔH ΔS ΔG Solubility (Sieverts) Plateau (Maxwell) Coexistence curve

Ronald Griessen

Andreas Züttel, Switzerland, 17.07.14 1 7

HYDROGEN ABSORPTION IN METALS α-Phase: Solid Solution MHx (0 < x < 0.1) H H, ΔV/V = k·cH β-Phase: Hydride Phase MHx x = {1, 2, 3,…} H H

R H Δ −

R S Δ

R S T R H p p Δ + ⋅ Δ − = $ $ % & ' ' ( ) ln

( )

H

c T k p p ln ln ⋅ ⋅ = " " # $ % % & ' 2 1

( )

H

c T k p p ln ln ⋅ ⋅ = " " # $ % % & ' 2 1

STABILITY OF HYDRIDES: VAN’T HOFF PLOT Tdec

Andreas Züttel, IfRES (2005) 19

THERMODYNAMICS OF HYDRIDES

ΔH0 = 2/n·(ΔHf,H - ΔHf,M) x A + y B + n/2 H2

H2

ΔHf,M x A + y B + n/2 H2 → AxBy + n/2 H2 → AxByHn

( ) ( )

( )!

" # $ % & Δ − Δ − Δ ⋅ = Δ

2

2 2 H H n B A H H B A H n H

y x n y x

( ) ( )

( )!

" # $ % & − − ⋅ = Δ

2

2 2 H S n B A S H B A S n S

y x n y x

S0(AxByHn) ≥ S0(AxBy) → (ΔS0( ≤(-S0(H2)( S0(H2) = 130 JK-1mol-1 AxByHn AxBy + n/2 H2 ΔHf,H ΔH

Andreas Züttel, Switzerland, 17.07.14 2

ELECTRONIC STRUCTURE

1) Lattice expansion reduces the band- width. 2) Attractive potential of the proton affects the metal states and leads to the metal- hydrogen band 5 to 8 eV below EF. 3) The H-H interaction results in new features in the lower part of the density of states for systems with more than one H atom per unit cell. 4) An upwards shift of EF results from the balance between the additional electrons brought in by hydrogen and the number of new states below EF. The balance between the ‘exothermic’ lowering of occupied states and the ‘endothermic’ upwards shift of EF d e t e r m i n e s t h e s t a b i l i t y o f t h e metalhydride. Ref.: L. Schlapbach, F. Meli, and A. Züttel, Chap. 21: “Intermetallic Hydrides and their Applications” in Intermetallic Compounds: Vol. 2, Practice, J. H. Westbrook and R. L. Fleischer (1994) John Wiley & Sons Ltd.

Bandstructure of LaNi5 and LaNi5H7

BINDING ENERGY

Ref.: Hammer B; Norskov J K, “Why Gold is the Noblest of all the Metals”, Nature 376, (1995), pp. 238-240

Energy antibonding bonding EF noble metal EF transition metal Adsorbate level

H s s, p d EF DoS E

Andreas Züttel, Switzerland, 17.07.14 2 2

SEMI-EMPIRICAL MODEL FOR THE STABILITY

The Local Band-Structure Model a = 18.6 kJ·mol-1HÅ4eV-3/2 b = -90 kJ·mol-1H

b R W E a H

j 4 j

+ ∑ ⋅ ⋅ Δ ⋅ = Δ

− ∞ Rj

Ref.: R. Griessen, Phys. Rev. B 38 (1988), pp.3690-3698 and V.L. Moruzzi, J. F. Janak, A.R. Williams, „Calculated Electronic Properties of Metals, Pergamon, New York (1978) ΔE W

EMPIRICAL MODELS: STABILITY

1) Reversed stability (global)

ΔH(ABnH2m) = ΔH(AHm) + ΔH(BnHm) - (1-F)·ΔH(ABn)

Miedema Model

Ref.: H.H. Van Mal, K.H.J. Buschow and A.R. Miedema, J. Less-Common Met. 35 (1974), pp. 65

2) Imaginary binary hydrides (local) AmBn + xH → (AmBnHx) interstitial site

ΔH([AaBb]H) = ΔH(AmHx·a/(a+b)) + ΔH(BnHx·b/(a+b))

binary hydrides

Ref.: I. Jacob, J.M. Bloch, D. Shaltiel and D. Davidov, Solid State Comm. 35 (1980),

• pp. 155.

Andreas Züttel, Switzerland, 17.07.14 2 4

INTERSTITIAL SITES IN METAL HYDRIDES HYDROGEN ON TETRAHEDRAL SITES HYDROGEN ON OCTAHEDRAL SITES

Ref: J. J. Reilly, G. D. Sandrock, Metallhydride als Wasserstoff-Speicher, Spektrum der Wissenschaften (April 1980), pp. 53-59

Andreas Züttel, University of Fribourg, 15.12.2002 25

FAMILIES OF HYDRIDE FORMING INTERMETALLICS Intermetallic Prototype Structure compound AB5 LaNi5 Haucke phases, hexagonal AB2 ZrV2, ZrMn2, TiMn2 Laves phase, hexagonal or cubic AB3 CeNi3, YFe3 hexagonal, PuNi3-typ A2B7 Y2Ni7, Th2Fe7 hexagonal, Ce2Ni7-typ A6B23 Y6Fe23 cubic, Th6Mn23-typ AB TiFe, ZrNi cubic, CsCl- or CrB-typ A2B Mg2Ni, Ti2Ni cubic, MoSi2- or Ti2Ni-typ

BODY CENTERED CUBIC SOLID SOLUTION ALLOYS

BCC Alloys: Ti-V-Mn, Ti-V-Cr, Ti-V-Cr-Mn, and Ti-Cr-(Mo, Ru)

Ref.: E. Akiba and M. Okada, “Metallic Hydrides III: Body-Centered-Cubic Solid-Solution Alloys”, MRS BULLETIN/SEPTEMBER 2002 699-703

V VH VH2 Structure fcc & hcp bcc Site O T O T Number 1 2 3 6 Size 0.414 0.255 0.155 0.291

DENSITY OF STATES FOR HYDROGEN

Andreas Züttel, Switzerland, 17.07.14 2 8

DENSITY OF STATES FOR HYDROGEN

Ref.: I. Bakonyi, F. Mehner, A. Rapp, A. Cziraki, E. Toth-Kadar, V. Skumryev, R. Reisser, H. Kronmüller and

• R. Kirchheim , Zeitschrift für Metallkunde (1993)

Andreas Züttel, Switzerland, 17.07.14 2 9

EMPIRICAL MODELS: GEOMETRY 1) Size of interstitial site: r > 0.37 Å Westlake criterion

Ref.: D. G. Westlake, J. Less-Common Metals 91 (1983), pp.275-292

2) Distance between hydrogen atoms: d > 2.1 Å

Ref.: A. C. Switendick, Z. Phys. Chem. N.F. 117 (1979), pp. 89

Number of hydrogen atoms:

Number of interstitial sites for which 1) and 2) applies.

ρV < 245 kg m-3

Andreas Züttel, Switzerland, 17.07.14 3

METAL HYDRIDES WITH SHORT H-H SEPARATIONS RTInH1.333 (R = La, Ce, Pr, or Nd; T = Ni, Pd, or Pt)

Ref.: P. Vajeeston et al. Phys. Rev. B 67 (2003), 014101 charge transfer electron density

CATALYZED HYDROGEN ABSORPTION

H2 activated Complex Desorption Recombination Adsorption Intercalation Mobility

• A. Züttel et al., LiBH4 a new

hydrogen storage material, Journal of Power Sources 118 (2003), pp. 1–7

• S. Orimo et al., "Dehydriding

and rehydriding reactions of LiBH4", Journal of Alloys and Compounds 404-406 (2005),

• pp. 427-430
• B. Bogdanovic, M. Schwickardi, Ti-

doped alkali metal aluminium hydrides as potential novel reversible hydrogen storage materials, Journal of Alloys and Compounds 253, 1-9 (1997).

1996 - 1997

• J. N. Huiberts, R. Griessen, J. H.

Rector, R. J. Wijngaarden, J. P. Dekker, D. G. de Groot, N. J. Koeman, Yttrium and lanthanum hydride films with switchable

• ptical properties, Nature 380,

231-234 (21 March 1996)

2003 - 2004

“LiBH2” “LiBH3.6” “LiBH3” LiH

STABILITY OF HYDRIDES

ΔH0 Elements Alloy Hydride Complex ΔHf ΔHdec

Li[BH4] LiH+B Li7B6 Li + B + H2

• 195

[kJ]

• 90
• 75 kJ/molH2

H2

Andreas Züttel, IfRES (2005) 34

THERMODYNAMICS OF HYDRIDES

ΔH0 = 2/(3n)·(ΔHf,C - ΔHf,P) A + n B + 2n H2

H2

ΔHf,P A + n B + 2n H2 → AHn + B + 3/2n H2 → A[BH4]n

[ ] ( ) ( ) ( )!

" # $ % & Δ − Δ − Δ ⋅ = Δ

2 4

2 3 2 H H n AH H BH A H n H

n n

( ) ( )

( )!

" # $ % & − − ⋅ = Δ

2

2 2 H S n B A S H B A S n S

y x n y x

S0(A[BH4]n) < S0(AHn + B) → (ΔS0( > (-S0(H2)( S0(H2) = 130 JK-1mol-1 A[BH4]n AHn + B + 3/2n H2 ΔHf,C ΔH

DEVELOPMENT*OF*THE*HYDROGEN*DENSITY*

5 10 15 20 25 1850 1900 1950 2000 2050 Year H/MH [mass%]

Pd* Mg2NiH4* NaAlH4* LiBH4* NH3BH3*

CH4* liquid*e.g.*Al[BH4]3*

!" +" Thomas"GRAHAM" Shin!Ichi"ORIMO" """""""""""Andreas"ZÜTTEL" Boris"BOGDANOVIC"

Andreas Züttel, IfRES (2005) 36

STABILITY OF BHn AND BHn-

Ref.: Puru Jena , Virginia Commonwealth University, Richmond, VA (to be published).

Gradient Corrected Density Functional Theory Energy gain in adding a H atom BHn-1 + H → BHn

Puru Jena

ADSORPTION ENERGY

[ ] ( )

( )

2 2 1 1

97

H M dis HH dis MM dis MH

X X H H mol kJ H − ⋅ + Δ + Δ ⋅ = ⋅ Δ

−

Pauling: Absorption Energy:

[ ]

( )

2 1

194

H M dis MM ads

X X H mol kJ H − ⋅ + Δ = ⋅ Δ

−

Pauling electronegativity

Ref.: Linus Pauling, “THE PRINCIPLES DETERMINING THE STRUCTURE OF COMPLEX IONIC CRYSTALS“, Journal of the American Chemical Society, 1929 - pubs.acs.org

Linus Carl Pauling

* 28. 2. 1901; † 19. 8. 1994 1954 Nobelprize for chemistry 1962 Nobelprize for peace

Andreas Züttel, IfRES (2005) 38

STABILITY OF COMPLEX HYDRIDES

M[BH4]n M, B, nH2

ΔH

ΔHdis M, B, H2 ΔHm ΔHMH = ΔHMM + 194·(XM - XH)2 [kJ / mol H] MHn + Bn + 3/2nH2 M[BH4]n ΔHf

0 = 247.4·XM - 421.2

[kJ / mol BH4] ΔHdis = ΔHf

0 - ΔHMH - ΔHm

Ref.: Y. Nakamori, K. Miwa, A. Ninomiya, H. Li, N. Ohba, S.-I. Towata, A. Züttel, and Shin-ichi Orimo, Physical Review B 74, 045126 (2006); Linus Pauling, THE PRINCIPLES DETERMINING THE STRUCTURE OF COMPLEX IONIC CRYSTALS, Journal of the American Chemical Society, 1929 - pubs.acs.org

Pauling Miwa, Orimo

50 100 150 200 10 20 30 Hydrogen density [kg/m3] Hydrogen density [kg H2/ 100kg storage material]

Andreas Züttel, Switzerland, 17.07.14

HYDROGEN DENSITY

carbon hydrates

• liq. hydro-

carbons metal hydrides comp. H2 gas

• liq. H2
• liq. natural

gas

NH3

complex hydrides physi- sorption

VCard: A. Züttel